Secreted clusterin inhibits keloid formation by promoting fibroblast apoptosis

Keloids are benign dermal proliferations resulting from excessive fibroblast activity that extends beyond the original site of injury. This study aims to investigate key biomarker genes associated with cell apoptosis and proliferation in the pathogenesis of keloids. Bioinformatic analysis of Gene Expression Omnibus datasets identified 122 differentially expressed genes (DEGs) in samples from keloid patients. Following the intersection with apoptosis-related genes (ARGs), three DEGs—ANLN, CLU, and SFRP2—were identified as keloid-associated ARGs. Among these, the expression of CLU was consistently reduced across both training and validation datasets. Experimental validation confirmed the expression alteration of CLU in keloid patient samples and further revealed that the expression of secreted CLU (sCLU) was significantly decreased in keloid fibroblasts. At the same time, BAX was down-regulated while BCL2 was up-regulated. Overexpression of sCLU in keloid derived primary fibroblasts significantly promoted apoptosis and reduced the viability of the cells, accompanied with up-regulated BAX and down-regulated BCL2, and fibrotic factor genes, such as collagen I, collagen III, α-SMA and CTGF. In contrast, serum levels of CLU did not differ significantly between keloid patients and non-related controls, suggesting limited utility of circulating CLU as a diagnostic biomarker. Taken together, these findings reveal a crucial role of sCLU in keloid pathogenesis, thereby presenting a potential tissue-level biomarker for keloid diagnosis and a promising therapeutic target.